Metallurgy,Microstructure and Properties of a New Nitride Strengthened Nickel‐Chromium Superalloy

The nitrogen content of Ni‐base superalloys for high temperature service is generally kept below about 0.05 wt.‐% to avoid detrimental precipitation of nitrides. These nitrides are said to have a harmful influence on mechanical properties and workability of these alloys. However, some recent studies and research conducted with nitrogen strengthening of Ni‐Cr‐alloys have resulted in an alloy with excellent physical and mechanical properties. The applied PESR (Pressurized Electro‐Slag Remelting)‐Technology provided up to 1.0 wt‐% nitrogen in a NiCr7030‐alloy.The homogeneously distributed nitrides prevent the alloy from excessive grain growth thus providing stable mechanical properties, i.e. impact toughness even after long term exposure. The new alloy easily exceeds R_m= 850 MPa at room temperature and 600 MPa at 600 °C as relevant design values. This paper introduces this new alloy with its very special metallurgy, microstructure, and its physical and mechanical properties.